Chiller of etch equipment for semiconductor processing

ABSTRACT

A chiller for etching equipment for processing a semiconductor includes: a chuck for controlling a temperature of a semiconductor wafer, a coolant pipeline connected to the chuck, a coolant tank connected to the coolant pipeline, an evaporator in the coolant tank, a refrigerant in the evaporator, a compressor for compressing refrigerant flowing from the evaporator, a condenser for condensing the compressed refrigerant from the compressor, and an electronically controlled expansion valve connected to the condenser to receive compressed refrigerant, and connected to the evaporator for feeding the expanded refrigerant into evaporator.

The present application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2007-0118230 (filed on Nov. 20, 2007), which is hereby incorporated by reference in its entirety.

BACKGROUND

Generally, a chiller is a temperature control device for stable process control in the manufacture of semiconductor devices. Among different semiconductor manufacturing processes, the chiller is mostly used in etching or exposing processes. The chiller maintains a constant temperature on a chuck or a chamber wall which may remove excess heat during the process. The maintenance of a constant temperature prevents overheating, which damages wafers, which in turn causes a decrease in productivity.

FIG. 1 is a schematic view illustrating construction of a chiller according to the related art. As illustrated in FIG. 1, a chiller 100 includes a chuck 30 on which a wafer 20 is positioned, a coolant (often, referred to as cooling water) pipeline 110 connected to the chuck 30, a coolant tank 120 and a circulation pump 130.

The coolant tank 120 has a silicone gasket interposed between a main body and a cover of the coolant tank to form a tight seal. The coolant tank 120 includes an inner space separated into a cooling bath 122 and a heating bath 123 by a partition panel 121 so as to receive a coolant up to a maximum level. The cooling bath 122 has an evaporator 134 placed therein which cools the coolant flowing into the cooling bath 122 through the coolant pipeline 110. The coolant flows into the heating bath 123 through a hole formed in the partition panel 121. The heating bath 123 has a heater 140 which heats the coolant to reach a desired temperature. Thus, the chiller 100 feeds the coolant with a controlled temperature through the coolant pipeline 110 to the chuck 30 to control temperature of the wafer 20 positioned on the chuck.

A detailed description will be given of a process of cooling (hereinafter, referred to as “refrigeration cycle”) the coolant via the evaporator 134 and another process of heating the coolant via the heater 140, along a refrigerant circulation flow path (arrow direction in FIG. 1) of a refrigerant (i.e., Freon gas). First, regarding the refrigeration cycle, the coolant is compressed in a compressor 131, and then condensed in a condenser 132. The refrigerant obtained from the condenser 132 is expanded in a thermal expansion valve 133. The expanded refrigerant undergoes heat exchange with the coolant in the cooling bath 122 via the evaporator 134, and then flows into the compressor 131. These processes form a repeating cycle. During the heating process, the refrigeration cycle is stopped and the heater 140 heated by power supplied from a heater driver heats the coolant in the heating bath 123 to reach a desired temperature.

FIG. 2 is a flow chart illustrating chiller equipment used for a related semiconductor processing installation. FIG. 3 is a table explaining conditions of the operational elements in the chiller equipment shown in FIG. 2 under temperature control. Generally, the temperatures required for the semiconductor processing installation 31 range from −20° C. to 80° C. A variety of methods for uniformly maintaining the temperature of a chamber in the processing installation 31 may be used. The temperature of the chamber may be increased, decreased and/or maintained by a refrigeration cycle and use of a heater.

Hereinafter, referring to FIGS. 2 and 3, the temperature control will be described in greater detail. The first type of control is a decrease of temperature with reference to a set temperature. For example, suppose that a set temperature is decreased from 80° C. to −20° C. A heater 21 has an output of “zero (O)” by Proportional Integral Derivative (PID) control, and is turned off. A refrigeration cycle is performed by operating, in order, a compressor 11, a condenser 12, a thermal expansion valve 14 for high temperature applications and an evaporator 17. Heat exchange occurs in the evaporator, which contains a coolant, thus decreasing the temperature (see second line in FIG. 3).

To attain an optimum temperature, a conversion temperature (for example, 25° C.) of each expansion valve for high temperature and low temperature applications may be set up. During the process of decreasing the temperature, if the temperature is over the conversion temperature, the temperature may be decreased through a refrigeration cycle proceeding, in sequence, with the compressor 11, the condenser 12, the thermal expansion valve 13 for low temperature applications and the evaporator 17. The thermal expansion valves (13 and 14) in the refrigeration cycle receive, in a feedback mode, heat of the evaporator 17 from sensitive heat tubes 18 and 19 attached on an outlet end of the evaporator 17 so as to control “degree of opening” of the thermal expansion valves 13 and 14. When the current temperature is reduced near to the set temperature (−20° C.), the heater 21 gradually sends output by PID control so as to complete stabilization of temperature.

The second type of control is an increase of temperature with reference to a set temperature. For example, suppose that a set temperature is increased from −20° C. to 80° C. The refrigeration cycle is stopped. The heater 21 produces heat at 100% output to elevate the temperature. When the current temperature is elevated near to the set temperature (80° C.), the refrigeration cycle is performed by PID output while the output of the heater 21 is suitably regulated by PID control, thus stabilizing the temperature (see first line in FIG. 3).

The third type of control is the maintenance of a set temperature. While maintaining the set temperature, the refrigeration cycle is always operating. The output of the heater 21 is regulated in a range of 0 to 100% by PID control. For example, suppose that the refrigeration cycle is continuously operated to continuously maintain a set temperature at 20° C. and stabilization of temperature (20° C.) has been attained with a heater output of about 85%. To reach another set temperature of 40° C., the refrigeration cycle is continuously operated by the same process as the refrigeration cycle for the set temperature of 20° C. However, even when the heater output increases to 100%, the output of the refrigeration cycle is relatively great compared to the heater 21, and stabilization of temperature at 40° C. may not be achieved. For this reason, a manual valve 15 for a first hot gas is opened to elevate the temperature of the refrigerant flowing into the evaporator 17 to decrease effective of the refrigeration cycle. In this way, stabilization of temperature may be achieved and the output of the heater 21 may be decreased below 100%.

As the set temperature increases, the output heater 21 is decreased. Therefore, opening another manual valve 16 for a second hot gas may pass the hot gas into the evaporator 17 so as to again reduce performance of the refrigeration cycle and decrease the output of the heater 21 (see third line in FIG. 3). To increase and maintain a desired temperature, using the heater only may cause excessive operation expenses. The system described above has problems in that degree of opening of the thermal expansion valve must be manually regulated at the initial stage in order to maintain a set temperature and, in addition, degree of opening of the manual valve for the hot gas must be manually controlled.

The whole temperature range cannot be sufficiently controlled by only one expansion valve and one valve for hot gas (sometimes, referred to as “a hot gas valve”). Accordingly, an increase in the number of thermal expansion valves for cooling purposes and the hot gas valves for heating purposes to maintain a set temperature of 40° C. results in increased initial construction cost and requires a complicated internal layout of a chiller. Moreover, if a heater for increasing and maintaining temperature malfunctions, extensive downtime may occur, thus reducing a rate of operation of a main apparatus.

SUMMARY

Embodiments relate to a chiller of etching equipment for semiconductor processing and, more particularly, to a chiller used with etching equipment for processing semiconductors, wherein the chiller may constantly maintain temperature of a chuck or a chamber wall, on which a wafer is positioned. Embodiments relate to an energy efficient chiller with reduced operational expenses in place of a heater for maintaining temperature.

Embodiments relate to a chiller of etching equipment for processing a semiconductor, including: a chuck for controlling a temperature of a semiconductor wafer, a coolant pipeline connected to the chuck, a coolant tank connected to the coolant pipeline, an evaporator in the coolant tank, a refrigerant in the evaporator, a compressor for compressing refrigerant flowing from the evaporator, a condenser for condensing the compressed refrigerant from the compressor, and an electronically controlled expansion valve connected to the condenser to receive compressed refrigerant, and connected to the evaporator for feeding the expanded refrigerant into evaporator. Opening degree of the electronic expansion valve may be regulated by PID control. The electronic expansion valve may be driven by a stepper motor.

Embodiments relate to a chiller for etching equipment for processing a semiconductor including: a chuck for controlling a temperature of a semiconductor wafer; a coolant pipeline connected to the chuck, a coolant tank connected to the coolant pipeline; a coolant circulation flow path including the coolant tank connected to the coolant pipeline and a circulation pump; a refrigerant circulation flow path including a condenser, an expansion valve, a refrigerant path in an evaporator fixed in the coolant tank, and a compressor; and an automatic valve for hot gas fixed in the coolant tank. The automatic hot gas valve may be driven by a stepper motor.

Embodiments relate to a method of operating a chiller for etching equipment for processing a semiconductor including: providing a semiconductor wafer, mounting the semiconductor wafer on a chuck, controlling the temperature of the wafer by circulating coolant from a coolant tank through a coolant pipeline connected to the chuck, circulating a refrigerant in an evaporator in the coolant tank to form evaporated refrigerant, compressing the evaporated refrigerant flowing from the evaporator to form compressed refrigerant, condensing the compressed refrigerant to form condensed refrigerant; expanding the condensed refrigerant using an electronically controlled expansion valve; and feeding the expanded refrigerant into evaporator.

For the chiller of etching equipment for processing a semiconductor according to embodiments, an electronic valve for hot gas and a heat exchanger may be used instead of a heater so as to reduce the down-time of a main apparatus caused by malfunction of the heater and to omit use of a hot thermal heater, thereby ensuring stability of products. In addition, operation and maintenance expenses may be minimized, enabling fabrication of an energy efficient chiller.

Furthermore, using only one electronic valve in place of plural hot gas valves may reduce the number of parts in a chiller so as to simplify a layout of the chiller, to reduce refrigerant leakage and, in particular, to easily perform preventive maintenance of the chiller, thereby increasing production of wafers.

DRAWINGS

FIG. 1 is a schematic view illustrating construction of a related chiller.

FIG. 2 is a flow diagram illustrating a chiller equipment included in a semiconductor processing installation.

FIG. 3 is a table explaining conditions of constitutional elements in the chiller equipment shown in FIG. 2 under temperature control.

FIG. 4A is a schematic view illustrating a related thermal expansion valve.

Example FIG. 4B is a schematic view illustrating an electronic expansion valve according to embodiments.

FIG. 5A is a schematic view illustrating a chiller of an etch equipment for processing a semiconductor, equipped with a heater, according to a related technique.

Example FIG. 5B is a schematic view illustrating a chiller of an etch equipment for processing a semiconductor, without any heater, according to embodiments.

DESCRIPTION

A chiller of an etch equipment for processing a semiconductor according to embodiments includes: a coolant tank receiving a refrigerant; a coolant pipeline for connecting a chuck, on which a wafer is positioned, and the coolant tank; a compressor for compressing the refrigerant flowing from the coolant tank; a condenser for condensing the compressed refrigerant from the compressor; and an expansion valve for expanding the condensed refrigerant from the condenser and for feeding the expanded refrigerant into the coolant tank, wherein the expansion valve is an electronic expansion valve with degree of opening controlled depending on temperature and/or pressure of the refrigerant which is present at one or more position(s) in a refrigerant circulation flow path consisting of the condenser, the expansion valve, the coolant tank and the compressor.

The chiller of an etch equipment for processing a semiconductor according to embodiments includes: a coolant pipeline for connecting a chuck, on which a wafer is positioned, and a chiller; a coolant circulation flow path including a coolant tank connected to the coolant pipeline and a circulation pump; a refrigerant circulation flow path including a condenser, an expansion valve, a refrigerant path in an evaporator fixed in the coolant tank, and a compressor; and an automatic valve for hot gas fixed in the coolant tank.

Hereinafter, the following detailed description will be given of technical constructions and functions of embodiments. As for the chiller for etching equipment for processing a semiconductor according to embodiments, a coolant circulation flow path including a coolant pipeline, a coolant tank and a circulation pump; a refrigerant circulation flow path including a condenser, an expansion valve, a refrigerant path in an evaporator and a compressor; and a heater installed in the coolant tank have substantially the same constructions as those in a related chiller, and therefore, further detailed description of these constructions will be omitted hereinafter for brevity and to prevent embodiments from being unclear. Operation of additional constructions and elements will become apparent from the following description.

FIG. 4A is a schematic view illustrating a related thermal expansion valve; example FIG. 4B is a schematic view illustrating an electronic expansion valve according to embodiments.

As illustrated in FIG. 4A, degree of opening of a typical thermal expansion valve 133 must be manually regulated at the initial stage in order to maintain the initial set temperature and, in addition, manual valves 15 and 16 for feeding a hot gas must be controlled.

As illustrated in example FIG. 4B, embodiments use an electronic expansion valve 150 for automatically controlling a refrigeration load and an automatically controlled valve for feeding a hot gas 160. Each of the electronic expansion valve 150 and the automatically controlled hot gas valve 160 receives digitized electrical signals as input data so that the valve exhibits degree of opening varied in a range of stage “0” (zero) to stage N by a stepper driving process, where N may be interpreted as a positive real number. The degree of opening of the electronic expansion valve 150 according to embodiments may be set based on a difference in temperatures measured at inlet and outlet ends of the evaporator and/or a pressure measured at the output end of the evaporator. The degree of opening of the electronic expansion valve 150 may be controlled by PID control, and may be, for example, driven by a stepper motor.

Accordingly, the degree of opening of the electronic expansion valve may be controlled by receiving temperature in feedback mode at a specific position in a flow path and by PID control using the received temperature. For example, when the set temperature is 20° C. and the current temperature is higher than 20° C., that is, a thermal load is applied, the electronic expansion valve receives the temperature in feedback mode and the degree of opening of the expansion valve is increased by PID control, so that a low temperature liquid refrigerant increasingly flows into the evaporator, thus decreasing temperature of a coolant which exchanges heat with the above refrigerant.

Conversely, if the current temperature is lower than 20° C., the electronic expansion valve receives this temperature in feedback mode and the degree of opening of the expansion valve is decreased by PID control, reducing the flow of the low temperature liquid refrigerant into the evaporator, thus elevating temperature of a coolant which exchanges heat with the above refrigerant.

As for the chiller for etching equipment for processing a semiconductor according to embodiments, a coolant circulation flow path including a coolant pipeline, a coolant tank and a circulation pump; and a refrigerant circulation flow path including a condenser, an expansion valve, a refrigerant path in an evaporator and a compressor have substantially the same constructions as those in a related chiller, and therefore, further detailed description of these constructions will be omitted hereinafter for brevity and to prevent embodiments from being unclear. Operation of additional constructions and elements will become apparent from the following description.

FIG. 5A is a schematic view illustrating a chiller of an etch equipment for processing a semiconductor, equipped with a related heater 140; and example FIG. 5B is a schematic view illustrating a chiller of an etch equipment for processing a semiconductor, without any heater, according to embodiments.

To increase and maintain a desired temperature, the heater 140, used alone, causes a problem with excessive expense in operation. Additionally, the whole range of temperature (i.e., −20° C. to 80° C.) cannot be sufficiently controlled by only one expansion valve and one hot gas valve. Therefore, the numbers of both the thermal expansion valves for cooling applications and the hot gas valves for heating applications increase, causing an increase in initial construction cost.

Accordingly, embodiments omit the heater 140 and provides a new chiller apparatus with reduced operational expenses (see example FIG. 5B). The following description will be given of a heating process according to embodiments.

After a hot gas compressed in a chiller passes a refrigeration cycle (condensation-expansion-evaporation-compression), using the resulting hot gas at 100° C. or more can eliminate requirement of any heater. Briefly, this is based on a principle that the compressed hot gas may be directly sucked into an expansion valve.

An automatic hot gas valve refers to a valve receiving digitized electrical signals as input data so that the degree of opening thereof is varied in a range of stage “0” (zero) to stage N by a stepper driving process, where N may be interpreted as a positive real number.

As a result, embodiments can provide an energy efficient chiller to reduce operational expenses without using a temperature preservation heater. Therefore, embodiments may eliminate problems in related techniques such as a complicated internal layout of the chiller, delays and down-time caused by heater malfunctions, etc.

Although embodiments have been described herein, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art. 

1. An apparatus comprising: a chuck for controlling a temperature of a semiconductor wafer; a coolant pipeline connected to the chuck; a coolant tank connected to the coolant pipeline; an evaporator in the coolant tank; a refrigerant in the evaporator; a compressor for compressing refrigerant flowing from the evaporator; a condenser for condensing the compressed refrigerant from the compressor; and an electronically controlled expansion valve connected to the condenser to receive compressed refrigerant, and connected to the evaporator for feeding expanded refrigerant into evaporator.
 2. The apparatus of claim 1, wherein a refrigerant circulation flow path is defined by the condenser, the expansion valve, the evaporator, the compressor, and connections therebetween, and wherein a degree of opening of the expansion valve is controlled with dependence on at least one of a temperature and a pressure of the refrigerant in at least one position in the refrigerant circulation flow path.
 3. The apparatus of claim 2, wherein the degree of opening of the expansion valve is controlled based on a difference in temperatures between refrigerant which flows from the condenser and refrigerant which flows from the evaporator tank into compressor.
 4. The apparatus of claim 2, wherein the degree of opening of the expansion valve is controlled based on a pressure of the refrigerant flowing from the evaporator to the compressor.
 5. The apparatus of claim 2, wherein the degree of opening of the expansion valve is controlled by proportional integral differential control.
 6. The apparatus of claim 5, wherein the expansion valve receives digitized electrical signals as input data.
 7. The apparatus of claim 6, wherein the degree of opening of the expansion valve is varied from stage zero to stage N by a stepper motor, where N is a positive real number.
 8. The apparatus of claim 1, wherein a degree of opening of the expansion valve is controlled based on a temperature of the refrigerant in the coolant pipeline.
 9. The apparatus of claim 2, wherein a degree of opening of the expansion valve is increased when the temperature of the refrigerant in at least one position in the refrigerant circulation flow path is higher than a set temperature.
 10. The apparatus of claim 2, wherein degree of opening of the expansion valve is decreased when the temperature of the refrigerant in at least one position in the refrigerant circulation flow path is lower than a set temperature.
 11. An apparatus comprising: a chuck for controlling a temperature of a semiconductor wafer; a coolant pipeline connected to the chuck; a coolant tank connected to the coolant pipeline; a coolant circulation flow path including the coolant tank connected to the coolant pipeline and a circulation pump; a refrigerant circulation flow path including a condenser, an expansion valve, a refrigerant path in an evaporator fixed in the coolant tank, and a compressor; and an automatic valve for hot gas fixed in the coolant tank.
 12. The apparatus of claim 11, wherein the automatic valve for hot gas is driven by a stepper motor.
 13. The apparatus of claim 12, wherein the stepper motor receives digitized electrical signals as input data.
 14. The apparatus of claim 13, wherein the degree of opening of the automatic valve is varied from stage zero to stage N by the stepper motor, where N is a positive real number.
 15. An method comprising: providing a semiconductor wafer; mounting the semiconductor wafer on a chuck;. controlling the temperature of the wafer by circulating coolant from a coolant tank through a coolant pipeline connected to the chuck; circulating a refrigerant in an evaporator in the coolant tank to form evaporated refrigerant; compressing the evaporated refrigerant flowing from the evaporator to form compressed refrigerant; condensing the compressed refrigerant to form condensed refrigerant; and expanding the condensed refrigerant using an electronically controlled expansion valve; and feeding the expanded refrigerant into evaporator.
 16. The method of claim 15, wherein a degree of opening of the expansion valve is controlled with dependence on at least one of a temperature and a pressure of one of the evaporated refrigerant, the compressed refrigerant, the condensed refrigerant, or the expanded refrigerant.
 17. The method of claim 16, wherein the degree of opening of the expansion valve is controlled based on a difference in temperatures between the condensed refrigerant and the evaporated refrigerant.
 18. The method of claim 16, wherein the degree of opening of the expansion valve is controlled based on a pressure of the evaporated refrigerant.
 19. The method of claim 16, wherein the degree of opening of the expansion valve is controlled by proportional integral differential control.
 20. The method of claim 15, wherein the expansion valve receives digitized electrical signals as input data. 